Laminate and method for manufacturing laminate

Abstract

A novel laminate having an electrode layer and a method for producing the same are provided. [Solution] A laminate comprising a resin substrate, a thermal expansion suppression layer formed on the resin substrate, and an electrode layer containing a sintered body of metal particles, wherein the thermal expansion suppression layer is formed from a curable resin containing a filler, and the electrode layer is formed on the thermal expansion suppression layer. A manufacturing method for the laminate includes the steps of: forming a thermal expansion suppression layer made from a curable resin containing a filler on the resin substrate; applying an ink containing metal particles onto the thermal expansion suppression layer; and sintering the metal particles.

Description

[Technical Field]

[0001] The present invention relates to a laminate and a method for producing the laminate. [Background technology]

[0002] Electrochromism is a phenomenon in which an applied voltage causes a redox reaction, resulting in a reversible color change. Electrochromic elements, which utilize this phenomenon and control the color by applying a voltage using electrochromic materials, are known.

[0003] An electrochromic element includes, for example, an electrochromic layer, which is an electronic functional layer that develops and loses color when a voltage is applied, and a transparent electrode. The transparent electrode is in contact with the electrochromic layer and is electrically connected to the electrochromic layer (see, for example, Patent Document 1).

[0004] Electrochromic sheets equipped with electrochromic elements are used, for example, as materials for eyewear such as sunglasses and wearable devices such as smart glasses. They are also used as light-adjusting components (optical filters) in window materials and imaging devices. They are also used in vehicle mirror devices as components for adjusting the reflected light of mirrors. As in the case of electrochromic elements, elements that electrically control the amount of light transmitted or the amount of light reflected / emitted by an electronic functional layer and a transparent electrode include organic EL elements and liquid crystal elements. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-167317 Summary of the Invention [Problem to be solved by the invention]

[0006] The transparent electrodes used in the configuration of Patent Document 1 are formed using a material having high electrical conductivity and high visible light transmittance. Known materials for transparent electrodes include oxides such as ITO (Indium Tin Oxide).

[0007] However, the above materials have higher electrical resistance than metal materials, so in an electrochromic layer sandwiched between transparent ITO electrodes, there are areas where current easily flows and areas where it does not, which can easily cause uneven color changes (coloring and decoloring) in the electrochromic layer.

[0008] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a novel laminate having an electrode layer and a method for producing the same. [Means for solving the problem]

[0009] In order to solve the above problems, the inventors have studied the configuration of the electrode layer. During the study, the inventors have found that when a resin substrate, which is more susceptible to thermal expansion than glass, is used as the substrate, the substrate thermally expands during the heating and baking process for forming the electrode layer, which makes it easy for film peeling and cracks to occur in the electrode layer. In other words, the inventors have found that there are cases in which the electrode layer cannot fully exhibit the functions expected of it. Based on this finding, the inventors have conducted extensive studies and completed the present invention.

[0010] In order to solve the above problems, one aspect of the present invention includes the following aspects.

[0011] [1] A laminate comprising a resin substrate, a thermal expansion suppression layer formed on the resin substrate, and an electrode layer containing a sintered body of metal particles, wherein the thermal expansion suppression layer is formed from a curable resin containing a filler, and the electrode layer is formed on the thermal expansion suppression layer.

[0012] [2] The laminate according to [1], further comprising one to three transparent electrode layers formed in contact with the electrode layer, the electrode layer being an auxiliary electrode layer containing the sintered body.

[0013] [3] The laminate according to [1] or [2], wherein the electrode layer is strip-shaped and has an average thickness of 4 μm or less in a cross section having a width of 150 μm from at least one end in the short direction of the electrode layer.

[0014] [4] The laminate according to any one of [1] to [3], wherein the electrode layer further contains an organic π-conjugated ligand.

[0015] [5] The laminate according to any one of [1] to [4], wherein the electrode layer has voids.

[0016] [6] The laminate according to any one of [1] to [5], wherein the resin substrate comprises a thermoplastic resin, and the glass transition temperature of the thermoplastic resin is 200° C. or lower.

[0017] [7] The laminate according to [2], wherein the transparent electrode layer contains indium oxide.

[0018] [8] The laminate according to any one of [1] to [7], which has been plastically deformed.

[0019] [9] The laminate according to any one of [1] to [8], wherein the electrode layer is electrically connected to a terminal for applying a voltage in a cross section in the thickness direction of the electrode layer.

[0020]

[10] A method for manufacturing a laminate, comprising the steps of: forming a thermal expansion suppression layer on a resin substrate, the thermal expansion suppression layer being made of a curable resin containing a filler; applying an ink containing metal particles onto the thermal expansion suppression layer; and sintering the metal particles.

[0021]

[11] The method for producing a laminate according to

[10] , wherein the sintering step is carried out by irradiating the metal particles with a laser. [Effects of the Invention]

[0022] According to the present invention, it is possible to provide a novel laminate having an electrode layer and a method for producing the same. [Brief explanation of the drawings]

[0023] [Figure 1] Fig. 1 is a schematic side view showing an example of the laminate of the present embodiment, which is also a schematic side view showing laminate 1-1 or 1-2 in Examples. [Figure 2] 2(a), 2(b), and 2(c) are schematic side views showing other examples of the laminate of this embodiment, where Fig. 2(a) is also a schematic side view showing laminates 2-1, 2-2, 3-1, and 3-2 in Examples. [Figure 3] 3(a) and 3(b) are schematic side views showing another example of the laminate of the present embodiment. [Figure 4] 4(a) and 4(b) are schematic side views showing another example of the laminate of the present embodiment. [Figure 5] 5(a), 5(b), 5(c), and 5(d) are schematic side views showing other examples of the laminate of this embodiment. [Figure 6] FIG. 6 is a schematic plan view showing a laminate 1-1 in the example. [Figure 7] FIG. 7 is a schematic plan view showing a laminate 1-2 in the example. [Figure 8] FIG. 8 is a schematic plan view showing a laminate 2-1 or 3-1 in the example. [Figure 9] FIG. 9 is a schematic side view showing the laminate 2-2 or 3-2 in the examples. [Figure 10] FIG. 10 is a schematic side view showing the laminate 2-3 or 3-3 in the example. DETAILED DESCRIPTION OF THE INVENTION

[0024] The laminate according to this embodiment and the method for manufacturing the laminate will be described below with reference to Figures 1 to 5. In all the following figures, the dimensions and proportions of the components are appropriately changed to make the drawings easier to understand.

[0025] <Laminate> As shown in Fig. 1, the laminate 10 includes a resin substrate 11, a thermal expansion suppression layer 12, and an electrode layer 13 containing a sintered body of metal particles. The thermal expansion suppression layer 12 is formed on the resin substrate 11 and is made of a curable resin containing a filler. The electrode layer 13 is formed on the thermal expansion suppression layer 12.

[0026] In the laminate 10 of this embodiment, by providing the thermal expansion suppression layer 12 on the resin substrate 11, even when a resin substrate 11 that thermally expands more easily than glass is used, peeling and cracking of the sintered body are less likely to occur in the electrode layer 13. As a result, the electrical resistance of the electrode layer 13 is less likely to be high in the laminate 10 of this embodiment. In other words, the laminate 10 of this embodiment can broaden the range of materials that can be selected for the resin substrate 11, and a thermoplastic resin that has excellent processability in heat bending processing of the laminate can be used for the resin substrate 11.

[0027] In this specification, the term "formed on resin substrate 11" means that thermal expansion suppression layer 12 is formed on resin substrate 11 directly or via another layer. In this specification, the term "formed on thermal expansion suppression layer 12" means that electrode layer 13 is formed on thermal expansion suppression layer 12 directly or via another layer. The other layers are not particularly limited as long as they are transparent, and examples thereof include an adhesive layer, a water vapor barrier layer, a gas barrier layer, and an optical adjustment layer.

[0028] [Resin substrate] When used as a back substrate for light-reflective and light-emitting elements, the resin substrate 11 can contain a non-transparent thermoplastic resin as its main material. On the other hand, when used as a light-transmitting surface substrate, it contains a transparent thermoplastic resin as its main material. Examples of thermoplastic resins include acrylic resins, polystyrene resins, polyethylene resins, polypropylene resins, polyester resins (polyethylene terephthalate (PET), polyethylene naphthalate (PEN), etc.), polycarbonate resins, polyamide resins, cycloolefin resins, vinyl chloride resins, polyacetal resins, triacetyl cellulose (TAC), etc. The resin substrate 11 may be made of one of the above resins, or a combination of two or more of them.

[0029] In particular, the resin substrate 11 preferably contains a thermoplastic resin having a glass transition temperature of 200° C. or less. The upper limit of the glass transition temperature is more preferably 180° C. or less, and even more preferably 160° C. or less. When the glass transition temperature is equal to or less than the upper limit, the resin substrate 11 has better thermal processability. The lower limit of the glass transition temperature is at least 80° C., preferably at least 100° C., and more preferably at least 120° C. When the glass transition temperature is at least the lower limit, the resin substrate 11 has better heat resistance. The above upper and lower limits can be arbitrarily combined for the glass transition temperature of the resin substrate 11. The thermoplastic resin having a glass transition temperature within the above temperature range is preferably a polycarbonate-based resin, a polyester-based resin, or a polyamide-based resin.

[0030] The resin substrate 11 may contain known fillers and additives.

[0031] The resin substrate 11 may be a single layer, or may be a laminate of two or three layers.

[0032] The average thickness of the resin substrate 11 is, for example, 0.05 mm or more and 10.0 mm or less, and preferably 0.1 mm or more and 5.0 mm or less.

[0033] The refractive index of the resin substrate 11 at a wavelength of 589 nm is preferably 1.3 or more and 1.8 or less, more preferably 1.4 or more and 1.65 or less. By setting the refractive index of the resin substrate 11 within this range, when the laminate of this embodiment is applied to an electrochromic sheet, its function can be improved.

[0034] [Thermal expansion suppression layer] The thermal expansion suppression layer 12 is made of a curable resin containing a filler. The thermal expansion suppression layer 12 is less susceptible to thermal expansion than the resin substrate 11. Therefore, deformation of the electrode layer 13 due to thermal expansion of the resin substrate 11 is suppressed during heating and baking of the electrode layer 13 or heating and bending of the laminate, and peeling and cracking of the electrode layer 13 are less likely to occur.

[0035] When the thermal expansion suppression layer 12 is formed on the rear substrate of a light-reflective or light-emitting element, the curable resin in the thermal expansion suppression layer 12 may contain a non-transparent thermoplastic resin or a photocurable resin as its main material. On the other hand, when the thermal expansion suppression layer 12 is formed on a light-transmitting substrate, the curable resin may contain a transparent thermosetting resin or a photocurable resin as its main material. Such curable resins are not particularly limited as long as they can suppress the thermal expansion of the resin substrate 11, but examples include acrylic resin, urethane resin, and epoxy resin. Resin materials with a higher glass transition temperature than that of the resin substrate 11 are particularly preferred. Having a higher glass transition temperature than that of the resin substrate 11 effectively suppresses deformation of the electrode layer 13 due to thermal expansion of the resin substrate 11 during heating and baking of the electrode layer 13 or during heating and bending of the laminate. The first thermal expansion suppressing layer 12 may be made of one of the above resins, or a combination of two or more of them.

[0036] The content of the curable resin in the thermal expansion suppressing layer 12 is not particularly limited, but may be 20% by mass or more and 99.9% by mass or less, and preferably 30% by mass or more and 90% by mass or less, based on the total amount of the thermal expansion suppressing layer 12.

[0037] The curable resin contains a filler. While the filler is not particularly limited, when the thermal expansion suppression layer 12 is formed on a light-transmitting substrate, a highly transparent material is preferred. The filler material may have a smaller coefficient of linear thermal expansion than the organic resin substrate 11. It is preferable to select an inorganic material (oxide, nitride, metal, etc.) from the viewpoint of a smaller coefficient of linear thermal expansion than the organic resin substrate. Examples of inorganic materials include silicon oxide, zirconia oxide, aluminum oxide, tin oxide, aluminum nitride, aluminum boride, various micas, Ag, Cu, Au, Ni, and carbon. Among these, silicon oxide, zirconia oxide, aluminum oxide, and tin oxide are more preferred as highly transparent filler materials. The filler material may also have a core-shell structure composed of multiple materials. The filler material may be surface-treated with a hydroxy group, an acrylic group, an epoxy group, or the like, from the viewpoint of suppressing aggregation of the filler or further improving mixability with the resin. The filler may be in the form of a sphere, fiber, flake, hollow particle, or the like. The particle size of the filler may be from 2 nm to 500 μm, preferably from 10 nm to 10 μm. Fillers of different shapes or particle sizes may also be mixed and used.

[0038] The filler content in the thermal expansion suppression layer 12 may be 1% by mass or more, and preferably 10% by mass or more and 200% by mass or less, based on the total amount of the curable resin. By adjusting the filler content within the above numerical range, the thermal expansion of the thermal expansion suppression layer 12 can be adjusted without impairing the effects of the present invention. For example, by increasing the filler content, the thermal expansion suppression layer 12 can be made less susceptible to thermal expansion. Furthermore, by reducing the filler content, the film quality of the thermal expansion suppression layer 12 can be further improved, and film defects can be further reduced.

[0039] The material of the thermal expansion suppression layer 12 may also contain known additives.

[0040] The thermal expansion suppression layer 12 may be a single layer or multiple layers.

[0041] The average thickness of the thermal expansion suppressing layer 12 is, for example, preferably 0.1 μm to 500 μm, more preferably 0.5 μm to 50 μm, and even more preferably 1 μm to 10 μm. When the average thickness of the thermal expansion suppressing layer 12 is within the above numerical range, peeling and cracking of the sintered body are less likely to occur during heating and firing of the electrode layer 13 or during heating and bending of the laminate. Furthermore, when the average thickness of the thermal expansion suppressing layer 12 is equal to or less than the above upper limit, peeling and cracking of the thermal expansion suppressing layer 12 itself are less likely to occur during heating and bending of the laminate.

[0042] The refractive index of the thermal expansion suppression layer 12 at a wavelength of 589 nm is preferably 1.3 or more and 1.8 or less, more preferably 1.4 or more and 1.65 or less. By setting the refractive index of the thermal expansion suppression layer 12 within this range, when the laminate of this embodiment is applied to an electrochromic sheet, the function thereof can be improved.

[0043] [Electrode layer] The electrode layer 13 includes a sintered body of metal particles. The electrode layer 13 may be formed on the entire surface of the thermal expansion suppression layer 12, or may be formed on a part of the surface.

[0044] The electrode layer 13 may contain a sintered body of metal particles. Examples of metal particles include particles of gold, silver, copper, aluminum, platinum, palladium, nickel, and tungsten. As the metal particles, one of these may be used, or two or more may be used in combination. Among these, silver particles or copper particles are preferred as the metal particles. The electrode layer 13 is formed by sintering metal particles through heat treatment, thereby enhancing the conductivity between the particles. In particular, when light is used as the heat treatment method, a light-absorbing material may be added to the electrode layer material to further enhance the efficiency of light sintering. Specific examples of such particles include infrared light-absorbing particles such as indium oxide, tungsten oxide, and LaB6. The size of the metal particles is preferably 2 nm or more and 500 nm or less, more preferably 2 nm or more and 100 nm or less. By having the size of the metal particles within the above numerical range, sintering can be performed at a lower temperature. Note that the metal particles may be a mixture of particles of different sizes.

[0045] In the laminate 10 of this embodiment, the thermal expansion suppression layer 12 is formed on the resin substrate 11, and therefore the thermal expansion suppression layer 12 prevents deformation of the electrode layer 13 even during heat treatment under temperature conditions that soften and deform the resin substrate 11. This makes it difficult for peeling and cracking to occur in the sintered body during heat sintering of the electrode layer 13 or during heat bending of the laminate. As a result, it is possible to obtain an electrode layer 13 that is less likely to have high electrical resistance.

[0046] The electrode layer 13 preferably further contains an organic π-conjugated ligand. By containing an organic π-conjugated ligand, metal particles The organic π-conjugated ligands are π-bonded to the metal particles, resulting in high conductivity due to the strong π-bonding and the close proximity between the particles. Here, π-bonding refers to the parallel bonding of the π-conjugated planes of the π-conjugated molecules to the surface of the metal particles, and is a strong interaction between the organic π-orbitals and the metal particle orbitals that occurs when the organic π-orbitals come close to the metal particle surface. Furthermore, organic π-conjugated ligands are organic ligands that act on the metal particles through such π-bonding.

[0047] The organic π-conjugated ligand is metal particles It is preferable that the surface-coordinated substituent has at least one selected from the group consisting of an amino group, a mercapto group, a hydroxy group, a carboxy group, a phosphine group, a phosphonic acid group, a halogen group, a cenol group, a sulfide group, and a selenoether group. The electrode layer 13 preferably contains a binder resin to enhance adhesion to the surface (base) on which it is formed. Examples of such materials include polyester and polyacrylic. The amount of binder resin added is preferably 5% by mass or less of the total amount of the electrode layer 13.

[0048] The electrode layer 13 preferably has voids, since this makes it less likely for the sintered body to peel or crack when the laminate is heated and bent. The electrode layer 13, which is made by sintering metal particles, has voids due to the contact shape between the particles. The voids can be confirmed by SEM observation, and the electrode layer 13 is preferably one in which voids of 5 μm or less can be confirmed by SEM observation.

[0049] The electrode layer 13 may be curved in plan view, and preferably has a continuous portion with a width in the short direction of, for example, 0.1 mm or more and 1.0 mm or less, more preferably 0.3 mm or more and 1.0 mm or less.

[0050] The average thickness of the electrode layer 13 is preferably 4 μm or less, more preferably 3 μm or less, and even more preferably 2 μm or less. More specifically, when the electrode layer 13 is strip-shaped, the upper limit of the average thickness of the electrode layer 13 is preferably 4 μm or less, more preferably 3 μm or less, and even more preferably 2 μm or less, in a cross section having a width of 150 μm from at least one end in the short direction of the electrode layer 13. When the electrode layer 13 is strip-shaped, the lower limit of the average thickness of the electrode layer 13 is not particularly limited, but examples thereof include 0.01 μm or more and 0.1 μm or more in a cross section having a width of 150 μm from at least one end in the short direction of the electrode layer 13. The upper and lower limits can be combined in any manner.

[0051] When the average thickness of the electrode layer 13 is within the above numerical range, peeling and cracking of the sintered body are less likely to occur during heating and sintering of the electrode layer 13 or during heating and bending of the laminate, and the electrical resistance of the electrode layer 13 is less likely to increase.

[0052] 2 to 5, the electrode layer 13 may be an auxiliary electrode layer 13a containing a fired body of metal particles. When the laminate 10 of this embodiment includes a transparent electrode layer 14 (14a, 14b, 14c) described later, the auxiliary electrode layer 13a is electrically connected to the transparent electrode layer 14.

[0053] 5(a) to 5(d), the electrode layer 13 may be electrically connected to a terminal (electrical connection layer) 15 for applying a voltage at a cross section in the thickness direction of the electrode layer 13. By electrically connecting the terminal 15 for applying a voltage from the end cross section of the laminate 10, a panel with a large surface size having functions such as electrochromism, a so-called narrow frame panel, can be formed. From the viewpoint of making it easier to electrically connect the terminal 15 for applying a voltage from the end cross section of the laminate 10, the thickness of the electrode layer 13 is preferably 0.5 μm or more.

[0054] The connection portion between the voltage application terminal 15 and the electrode layer 13 may have an uneven shape. That is, the connection portion may be formed by meshing an uneven shape formed on the voltage application terminal 15 with an uneven shape formed on the electrode layer 13. This ensures a larger contact area between the voltage application terminal 15 and the electrode layer 13 at the connection portion. As a result, the connection resistance of the connection portion can be further reduced. In addition to the connection portion between the voltage application terminal 15 and the electrode layer 13, the connection portion between the voltage application terminal 15 and the resin substrate 11, the connection portion between the voltage application terminal 15 and the thermal expansion suppression layer 12, and the voltage application terminal 15 and the transparent electrode layer 14 may also have an uneven shape. This further reduces the connection resistance of the connection portion and increases the mechanical connection strength.

[0055] In addition, at the connection portion between the terminal 15 for applying voltage and the electrode layer 13, the resin substrate 11, the thermal expansion suppression layer 12, or the transparent electrode layer 14, an uneven shape may be set only at the connection portion with the electrode layer 13, or an uneven shape may be set at least at the connection portion with the electrode layer 13, or an uneven shape may be set in all layers.

[0056] Furthermore, when a concave-convex shape is set in all layers, the mechanical connection strength between the terminal 15 for applying voltage and each layer can be particularly increased, and the efficiency of processing the concave-convex shape can be further improved. Specifically, a process sequence can be adopted in which, after all layers are laminated, grooves are formed on the side surfaces of the laminate, and then the terminal 15 for applying voltage is formed so as to fill the grooves. This allows the concave-convex shape to be processed more efficiently.

[0057] (Transparent electrode layer) As shown in Figures 2 to 5, when the electrode layer 13 is an auxiliary electrode layer 13a containing metal particles, it may be provided with one to three transparent electrode layers 14 (14a, 14b, 14c) formed in contact with the auxiliary electrode layer 13a.

[0058] The transparent electrode layer 14 is transparent. Examples of materials for the transparent electrode layer 14 include oxides such as ITO, FTO (F-doped tin oxide), ATO (antimony tin oxide), IZO (indium zinc oxide), In2O3, SnO2, and Al-containing ZnO, as well as Au, Pt, Ag, Cu, and alloys containing these elements, carbon, and conductive polymers. The transparent electrode layer 14 may be made of one of these materials, or two or more of these materials may be combined. Metallic materials with low transparency can be used as transparent electrodes by thinning them or increasing the voids by forming them into a lattice shape. Among these, materials containing indium oxide are preferred for the transparent electrode layer 14, as they provide superior density and transparency to the transparent electrode layer 14. ITO, IZO, ITO, or In2O3 are more preferred, and ITO is even more preferred. When the transparent electrode layer 14 contains these preferred materials, the density is further improved, making it easier to protect the inside of the device from moisture and oxygen. This further improves the durability of the device.

[0059] The thickness of the transparent electrode layer 14 is adjusted to ensure the required transparency. Alternatively, when two laminates 10 of this embodiment are used to create an electrochromic sheet, the thickness is adjusted to ensure the required transparency and to obtain an electrical resistance value that allows an appropriate current to flow through the electrochromic sheet layer, which changes color when a voltage is applied. When ITO is used as the material for the transparent electrode layer 14, the average thickness of the transparent electrode layer 14 is, for example, 50 nm to 200 nm, preferably 50 nm to 150 nm, and more preferably 60 nm to 130 nm.

[0060] 2(a) to 2(c), when the laminate 10 of this embodiment forms one transparent electrode layer 14a, the transparent electrode layer 14a may be formed in contact with the upper part, lower part, or thickness direction cross section of the auxiliary electrode layer 13a. Furthermore, the transparent electrode layer 14a may be formed on the entire surface of the thermal expansion suppression layer 12, or may be formed on only a part of it.

[0061] As shown in Figures 3(a) and 3(b), when the laminate 10 of this embodiment forms two transparent electrode layers 14a and 14b, the transparent electrode layer 14a and the transparent electrode layer 14b sandwich the auxiliary electrode layer 13a. In this case, the transparent electrode layer 14a may be formed on the entire surface of the thermal expansion suppression layer 12, or on a portion thereof. The transparent electrode layer 14b may be formed on the entire surface of the auxiliary electrode layer 13a, or on a portion thereof. Furthermore, the transparent electrode layer 14a and the transparent electrode layer 14b may be formed of the same material or different materials.

[0062] Furthermore, as shown in FIGS. 4(a) and 4(b), the laminate 10 of this embodiment may form third transparent electrode layers (14a, 14b, and 14c). In this case, the transparent electrode layers 14a and 14b are the same as those in the second transparent electrode layers 14a and 14b. The transparent electrode layer 14c is formed in contact with the thickness-direction cross section of the auxiliary electrode layer 13a. In this case, the transparent electrode layer 14c may be in contact with the entire thickness-direction cross section of the auxiliary electrode layer 13a, or may be in contact with only a portion of the thickness-direction cross section.

[0063] The laminate 10 of this embodiment may be plastically deformed because peeling and cracking of the sintered body are less likely to occur in the electrode layer 13. More specifically, the laminate may be partially or entirely plastically deformed by heat bending. The shape of the plastically deformed laminate may be a convex shape, a concave shape, or a 3D curved shape.

[0064] <<Laminate manufacturing method>> The manufacturing method of the laminate 10 of this embodiment includes a step of forming a thermal expansion suppression layer 12 on a resin substrate 11 using a curable resin containing a filler as a forming material (hereinafter also referred to as the ``thermal expansion suppression layer forming step''), a step of applying an ink containing metal particles onto the thermal expansion suppression layer 12 (hereinafter also referred to as the ``applying step''), and a step of sintering the metal particles (hereinafter also referred to as the ``sintering step'').

[0065] [Thermal expansion suppression layer formation process] A thermal expansion suppression layer 12 is formed on a resin substrate 11 using a curable resin containing a filler as its forming material. For example, the thermal expansion suppression layer 12 can be formed by a crosslinking reaction or polymerization reaction of a heat- or light-curable compound. More specifically, the thermal expansion suppression layer 12 can be formed by applying a composition containing a filler and a heat- or light-curable polyfunctional monomer or polyfunctional oligomer onto the resin substrate and then crosslinking or polymerizing the polyfunctional monomer or polyfunctional oligomer. Examples of the coating method include conventional wet coating methods such as spin coating, bar coating, gravure coating, slit coating, screen printing, dispensing, and ink jet.

[0066] [Coating process] Droplets of ink containing metal particles are applied onto the thermal expansion suppression layer 12. Specifically, the same wet coating method as used in the thermal expansion suppression layer formation process can be used. When patterning the electrode layer 13, it is preferable to apply the ink by inkjet printing or screen printing.

[0067] The ink containing metal particles preferably contains the above-mentioned organic π-conjugated ligand. metal particles It is preferable that the compound has at least one substituent selected from the group consisting of a hydroxy group, a carboxy group, an amino group, an alkylamino group, an amide group, an imide group, a phosphonic acid group, a sulfonic acid group, a cyano group, a nitro group, and salts thereof, which is a substituent that makes the compound soluble in aqueous solvents and alcoholic solvents. Furthermore, the ink containing metal particles preferably contains a surfactant or binder resin from the viewpoint of improving wettability and adhesion to the surface (base) on which the ink is formed. Examples of surfactants include common materials such as anionic and cationic surfactants. Examples of binder resin materials include polyester and polyacrylic. The amount of surfactant added is preferably 1% by mass or less of the total amount of the ink containing metal particles. The amount of binder resin added is preferably 5% by mass or less of the total amount of the ink containing metal particles.

[0068] [Sintering process] After the coating step, the metal particles are sintered to form the electrode layer 13. The sintering method is not particularly limited as long as it can produce a sintered body of the metal particles. Examples include local heating methods such as plasma treatment, dielectric heating treatment, excimer light irradiation treatment, flash lamp light irradiation treatment, ultraviolet treatment, microwave treatment, infrared heater treatment, and hot air heater treatment. Among these, it is preferable to sinter the metal particles by irradiating them with a laser. When irradiating the metal particles with a laser, it is possible to selectively heat only the metal particles by selecting a laser wavelength that is not absorbed by the resin substrate 11. Therefore, thermal deformation of the resin substrate 11 can be further suppressed. Specifically, the laser wavelength is preferably an infrared wavelength or a visible light wavelength.

[0069] The manufacturing method of the laminate 10 of this embodiment may further include a step of forming one to three transparent electrode layers 14 in contact with the electrode layer (hereinafter also referred to as a "transparent electrode layer forming step"). The transparent electrode layer forming step can be performed using a known method after the thermal expansion suppression layer forming step or the sintering step. That is, when the transparent electrode 14 is mainly made of an organic material such as a conductive polymer, it can be easily formed by coating ink containing the organic material using a coating method such as spin coating, bar coating, gravure coating, slit coating, screen printing, dispensing, or inkjet printing. Furthermore, when the ink is a photocurable or thermosetting material, it is coated, dried, and then cured using light, heat, or the like. On the other hand, when the transparent electrode 14 is made of an inorganic material, it can be easily formed by a vacuum film forming method such as sputtering, vacuum deposition, or ion plating. [Example]

[0070] The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0071] [Example 1] (Preparation of laminate) First, a polycarbonate sheet (trade name: PC2151, manufactured by Teijin Limited) having a thickness of 0.3 mm and a glass transition temperature of 146° C. was prepared as the resin substrate 11. An acid-modified epoxy urethane acrylate oligomer resin (trade name: ZCR6001H, manufactured by Nippon Kayaku Co., Ltd., softening temperature after curing: 198°C), which is a curable resin material, was prepared as the main material for the thermal expansion suppression layer 12. In addition, an inorganic particle propylene glycol monomethyl ether dispersion (trade name: PGM-AC2140Y, manufactured by Nissan Chemical Co., Ltd., methacrylic surface treatment, average particle size: 10 nm to 15 nm, SiO2) was prepared as the inorganic filler to be contained in the curable resin.

[0072] The inorganic filler was added to the curable resin so that the content of the inorganic particles was 150% by mass relative to the total amount of the curable resin, and then a photoinitiator (product name: Omnirad TPO H, manufactured by IGM Resins BV) was added in an amount of 4% by mass relative to the total amount of the curable resin to prepare a coating solution.

[0073] The resulting coating solution was diluted with 2-ethoxyethanol and then coated onto the surface of a polycarbonate sheet using a bar coater. The coating solution was then dried at 80°C for 5 minutes and cured by UV irradiation to form a thermal expansion suppressing layer 12 with an average thickness of 2 µm. The sheet thus obtained was cut into an oval sheet having a major axis of 75 mm and a minor axis of 55 mm.

[0074] Next, a water-based Ag nanoparticle ink containing an organic π-conjugated ligand (product name: Dry Cure Ag-JB 0420B, manufactured by C-INK) was prepared. The aqueous Ag nanoparticle ink was inkjet coated (precision core i1600, Epson head-mounted machine) onto the oval sheet to form a frame-shaped electrode layer 13 (length 43 mm, width 0.7 mm, average thickness 2 μm) formed by dividing a rounded square (corresponding to a side of 45 mm) in half. After coating, the resulting laminate 10 was baked in an oven at 120°C for 30 minutes to form the electrode layer 13, yielding a laminate 1-1 of Example 1 (side view: FIG. 1, plan view: FIG. 6).

[0075] In addition, laminate 1-2 of Example 1 (side view: Figure 1, plan view: Figure 7) was obtained for electrical resistance evaluation in the same manner as laminate 1-1, except that an electrode layer 13 having a square shape with sides of 10 mm and an average thickness of 2 μm was formed.

[0076] (Evaluation of laminate) When the electrode layers 13 of the laminates 1-1 and 1-2 were observed under a microscope, no peeling or cracks were found. The electrical resistance of both ends of the electrodes (between 10 mm width) of the laminate 1-2 was measured with a tester and found to be 4 Ω or less.

[0077] [Example 2] (Preparation of laminate) In the same manner as in Example 1, a thermal expansion suppression layer 12 was formed on the surface of a polycarbonate sheet.

[0078] A sputtering device (manufactured by Solaris Evatec Co., Ltd.) was used to form a transparent electrode layer 14a made of ITO with a thickness of 100 nm on the formed thermal expansion suppression layer 12. The sheet obtained as described above was cut into an oval sheet with a major axis of 75 mm and a minor axis of 55 mm.

[0079] Next, a water-based Ag nanoparticle ink containing an organic π-conjugated ligand (product name: Dry Cure Ag-JB 0420B, manufactured by C-INK) was prepared. The aqueous Ag nanoparticle ink was inkjet coated (precision core i1600, Epson head-mounted machine) onto the oval sheet to form a frame-shaped electrode layer 13 (length 43 mm, width 0.7 mm, average thickness 2 μm) formed by dividing a rounded square (corresponding to a side of 45 mm) in half. After coating, the resulting laminate 10 was baked in an oven at 120°C for 30 minutes to form an auxiliary electrode layer 13a, yielding a laminate 2-1 of Example 2 (side view: FIG. 2(a) , plan view: FIG. 8 ).

[0080] In addition, a laminate 2-2 of Example 2 (side view: Figure 2(a), plan view: Figure 9) was obtained for electrical resistance evaluation in the same manner as the laminate 2-1, except that an auxiliary electrode layer 13a having a square shape with sides of 10 mm and an average thickness of 2 μm was formed.

[0081] Furthermore, two laminates 2-1 were bonded together with an OCA sheet 16 (LA-50, manufactured by Nitto Denko Corporation) with the auxiliary electrode layers 13a facing inward, forming a configuration in which two transparent electrode layers were formed (side view: Figure 10). The bonded laminate was then thermally plastically deformed using a thermoforming machine to obtain laminate 2-3, which was 3D processed to a curvature radius of 130 mm. For the thermoforming process, a concave mold and a convex mold with a curvature radius of 130 mm made from STAVAX material were prepared, and the temperatures of the concave and convex molds were adjusted to 146°C. The sheet-like laminate was adsorbed onto the concave mold and sandwiched between the convex molds.

[0082] (Evaluation of laminate) Microscopic observation of the auxiliary electrode layers 13a of the laminates 2-1, 2-2, and 2-3 revealed no peeling or cracks. The electrical resistance of both ends of the electrodes of the laminate 2-2 (across a 10 mm width) was measured with a tester and found to be 1.5 Ω or less.

[0083] [Example 3] (Preparation of laminate) Laminates 3-1, 3-2, and 3-3 of Example 3 were obtained in the same manner as in the laminates 2-1, 2-2, and 2-3 of Example 2, except that the average thickness of the auxiliary electrode layer 13a was changed from 2 μm to 4 μm.

[0084] (Evaluation of laminate) When the auxiliary electrode layers 13 of the laminates 3-1 and 3-2 were observed under a microscope, only slight peeling was confirmed in some areas, but it was not to the extent that it affected the electrical conductivity. Microscopic observation of the auxiliary electrode layer 13a of the laminate 3-3 revealed that the degree of peeling of the auxiliary electrode layer 13a was the same as that of the laminate 3-1. The electrical resistance of both ends of the electrodes (between 10 mm width) of the laminate 3-2 was measured with a tester and found to be 0.8Ω or less.

[0085] [Example 4] (Preparation of laminate) Laminates 4-1, 4-2, and 4-3 of Example 4 were obtained in the same manner as in the method for laminates 2-1, 2-2, and 2-3 of Example 2, except that the inkjet-coated auxiliary electrode layer 13a was dried at 95°C for 30 minutes and then photo-baked with an infrared laser. The laser light source was CW, wavelength 940 nm, 360 W, irradiation spot size: 80 mm × 2 mm (laser light source L13920-711 manufactured by Hamamatsu Photonics K.K.). An irradiation unit A133933-13W (manufactured by Hamamatsu Photonics K.K.) was used, and the scanning speed was set to 150 mm / sec.

[0086] (Evaluation of laminate) Microscopic observation of the auxiliary electrode layers 13a of the laminates 3-1, 3-2, and 3-3 revealed no peeling or cracks. The electrical resistance of both ends of the electrodes (between 10 mm width) of the laminate 3-2 was measured with a tester and found to be 1.2Ω or less.

[0087] [Comparative Example 1] (Preparation of laminate) Laminates 5-1 and 5-2 of Comparative Example 1 were produced in the same manner as in the laminates 1-1 and 1-2 of Example 1, except that the thermal expansion suppressing layer 12 was not formed.

[0088] (Evaluation of laminate) Microscopic observation of the electrode layers 13 of the laminates 5-1 and 5-2 revealed fine cracks. The electrical resistance of both electrode ends (a 10 mm width) of the laminate 5-2 was measured with a tester and found to be 7 Ω or more. [Explanation of symbols]

[0089] 10...Laminate, 11...Resin substrate, 12...Thermal expansion suppression layer, 13...Electrode layer, 13a...Auxiliary electrode layer, 14 (14a, 14b, 14c)...Transparent electrode layer, 15...Voltage application terminal, 16...OCA sheet

Claims

1. A resin substrate; a thermal expansion suppression layer formed on the resin substrate; an electrode layer including a sintered body of metal particles; the thermal expansion suppression layer is formed from a curable resin containing a filler; The electrode layer is formed on the thermal expansion suppression layer.

2. The device further comprises one to three transparent electrode layers formed in contact with the electrode layer, The laminate according to claim 1 , wherein the electrode layer is an auxiliary electrode layer comprising the sintered body.

3. 3. The laminate according to claim 1, wherein the electrode layer is strip-shaped and has an average thickness of 4 μm or less in a cross section having a width of 150 μm from at least one end in a short direction of the electrode layer.

4. The laminate according to claim 1 or 2, wherein the electrode layer further comprises an organic π-conjugated ligand.

5. The laminate according to claim 1 or 2, wherein the electrode layer has voids.

6. the resin substrate comprises a thermoplastic resin, The laminate according to claim 1 or 2, wherein the thermoplastic resin has a glass transition temperature of 200°C or lower.

7. The laminate of claim 2 , wherein the transparent electrode layer comprises indium oxide.

8. 3. The laminate of claim 1 or 2, which has been plastically deformed.

9. The laminate according to claim 1 or 2, wherein the electrode layer is further electrically connected to a terminal for applying a voltage in a cross section in the thickness direction of the electrode layer.

10. forming a thermal expansion suppression layer on a resin substrate, the thermal expansion suppression layer being made of a curable resin containing a filler; applying an ink containing metal particles onto the thermal expansion suppression layer; and a step of sintering the metal particles.

11. The method for producing a laminate according to claim 10 , wherein the sintering step is performed by irradiating the metal particles with a laser.

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